A major objective of this research is to develop improved methods of calculating absorption and circular dichroic spectra of complex molecules from empirical data characterizing the groups in the molecule. The role of the solvent medium will be explored in particular. A related goal is that of calculating electrostatic energies of polar molecules in the presence of solvent for use in predicting chemical equilibria. The main theoretical model is a multipole interaction model, in which the groups in a molecule are assumed not to exchange charges and to interact by way of the fields of their multipole moments. Parameters characterizing the groups are determined semiempirically using optimization methods.